Safety system for railway cars



. May 10, 1927.

H. ROWNTREE SAFETY SYSTEM FOR RAILWAY CARS Filed March 25. 1922 4 Sheets-Sheet 1 I grmzqgex 7 BY ATTORNEY H. ROWNTREE SAFETY SYSTEM FOR RAILWAY CARS May 10 1927.

Filed March 25, 1922 4 Sheets-Sheet 2 INVENTOR (4mm t H. ROWNTREE SAFETY SYSTEM FQR RAILWAY CARS May/10.1927. 36 21748 Filed Mare}; 25. 1922 4 Sheets-Sheet 3 Q v I INVENTOR I my Aflogg- 4 1 5 1,52 7 May 9' 1927' H. ROWNTREE SAFETY SYSTEM RAILWAY CARS Fil d March 25. 1922 4' Sheets-Sheet 4 INVENTOR hm I mmilmi Q {BY pM -ATTORNEYQ Patented May 10,1927.

lll'll'ExD STATES IT. Y., 'ASSIGNOB' T NATIONAL ENEUMATIC HAROLD ROIR NTREE, OF NEW YORK,

, 1,627,748 PATENT OFFICE.

COMPANY, OF NEW YORK, N. Y., A CORPORATION OE WEST VIRGINIA.

SAFETY SYSTEM FOR RAILWAY cans.

Application filed March 25, 1922. Serial No; 546,844.

This invention relates to systems for ensuring safety to railway trains, 'irrthat it is directed to the provision of exceedingly simple andeiiicicnt means, instrumentalities and systems for the prevention of collision between trains on the same track.

The object of the invention is to provide a system of instrumentalities for usein connection therewith, which is simple, efficient, economical of manufacture and maintenance, which will prevent collision between trains on the same track.

A further object of the invention is to provide a system of the character set forth, which requires little equipment in addition to the standard equipment at present employed, and which limits the safety system in its application to prescribed areas between trains, and the relative speed of travel of the respective trains.

Further objects of the invention will appear more fully hereinafter.

' The invention consists substantially in the construction, combination. locationand relative arrangei'nent of parts, and in essence the method or the system employed in connection therewith, all as will be morefully hereinafter set forth, shownby the accon'ipanyi drawings and finally pointed out in the appended claims.

Referring to the drawings,

Fig. 1 a diagrammatic view showing a railway with two trains operating thereon in the same direction, and illustrating the system of my invention;

- Fig, 2 a schematic diagram showing the apparatus employed in connection with my invention, which is located on the car or train;

Fig. 3 is a view in front elevation of what I will term a meter employed in accordance with my invention, showing the electric circuits employed in connection therewith;'

i a top. plan view of the same;

i 5 is a view in side elevation thereon;

i m. is a view in front elevation showin modified form of meter employed in accordance with myinvention, and which I may term the preferred fo m thereof;

F 7 a viewin side elevation ofthe same;

Fig. 8 is a sectional view taken on the line 8-; of Fig". 6, and looking in the direction of the arrows;

Fig. 9 is a sectional view taken on the line 9 9, Fig. 6, and looking in the direction of the arrows.

Figs. 10 and 11 are views similar to Fl. 1, showing modified arrangements embodying my invention. 1

Fig; 12 is a view largely diagrammatic showing various positions of thespeedometer rod and the bridging members.

The same part is designated by the same reference character wherever it occurs throughout the several views.

lVhile I have shown and will describe my inventionas applied to the operation of cars coupled up into trains, it is to be understood that the invention is equally well adapted for use in connection with the operation of single cars, and, therefore, wherever I refer to near or to a train, it is to be understood that in either case a single car or two or more cars coupled up into a train consisting of one or more cars is intended and in cluded. In Letters Patent No. 1,278,221, granted to me September 10, 1918, I have shown and described a railway block system wherein the speecl'oftravel of a car or train is controlled by that of a car or train operating in advance of it over the same track, and wherein this cont-r01 is automatic, and further, wherein the control is secured by the conjoint action of the speed and distance ahead of the preceding train. In general, the system of my present invention is designed to obtain the same results, that is, under this system which comprises my present invention, I control the train, whereby the propelling power thereof is automatically cut off, and the brakes automatically applied when, but only as long as, the train is within what I term the danger zone that follows after the train ahead.

In the operation of the railway systems,

there is a danger zone in the rear of each train, into which it is unsafe for a following train to enter. Manifestly an arbitrary and fixed danger zone could be established so large that. itw ould be absolutely safe under all possible conditions, but this would place a serious handicap upon the possibilities of the system, and it is highly important that the danger zone should not be larger than is necessary for safety. I, therefore, vary the size of the danger zone under different situations, so as to leave the maximum of freedom of speed consistent with safety. I

In the first place I reduce its necessary size by doing away withfixed danger zones, and employing a floating danger zone between trains. in the second place I vary it by the speed of the train that is being controlled, the faster the speed the large..- the field of the danger zone ahead. .ln the third place I vary it by whether the distance between trains is increasing or decreasing, a decreasing distance enlarging the danger zone. In the fourth place I vary all these conditions to suit the rradient,so that the danger zone islarggerunder the same conditions on a down grade than on a level. In the fifth place I ive a signal, in. advance, that the danger zone is im minent. In one form of my invention, so. long as the train in front is more than a varying. predetermined distance ahead, no automatic control is obtained. lvhenever this separating distance less than the prcdetermined distance, or danger zone,v then the automatic control will go into effect whenever the speed of that train exceeds the speed of the train ahead. and the train will be automatically liberated from automatic control as soon as the speed of the trainhas been reduced toa slower speed than the speed of the train ahead.

It will readily be apparent that by means of such a system all the trains can; proceed. even when comparatively close togetl'ier, so long as the separating. distance is not being lessened". If a train running at a high rate of speed approaches within a predetermined distance of a train running: at a lower rate of speed, the speed of the second train "ill be automatically reduced until the separating distance ceases becoming; less, and commences to. increase. when the automatic control of the same train will cease. unless the separating. distance again decreases. Within a predetermined distance. therefore, the automatic control. operates, when there is a decreasing separating distance between trains, and ceases to operate when there is an increasing separating distance between trains.

There are many different constructions that might be employed to produce these results, each having its special advz-inta es and disadvantages. In my issued patent. above identified, I have shown and described in detail one construction which is of an electip-mechanical design. The tendency of mechanical parts to .lrnoclr to pieces when a mechanical. movement is ransmitted to or from a fast moving; train. from or to a stationary mechanism on the right of way. is so well. known and so :hfiicult to overcome that it appears obvious that the possibilities of non-operation through a failure of the electric energy, which is. of course, possible, would be more remote than the probabilities of mechanical trouble. Furthermore, a failure of electrical energy can be made to play to safety, while a breakage of mechanical parts can not. One of the fundamental purposes of my present invention, therefore, is to provide a system which will accomplish the broad general objects of by issued patent, but entirely electrically as distinguished from electro-inecha-nically, thereby completely avoiding the fundamental disadvantage of mechanical parts, the great possibility of non-operation, and the expense. incident to continual replacements due, to vibration and shock transmitted be tween moving and stationary parts. I

A further and. important purpose of my invention is toprovide a system of such character that the failure of any part to properly function, or any other abnormal condition, will ensure the safety of the car or train, and consequently ofits passengers. In other words,l provide a system whereby the existence of any abnormal. condition brings the safety device into operation..

As illustrative of the principles of my invention, I have shown means for accomplishing the purpose thereof. The specific structure. arrangement and instrumental'ities employed therefor. I, however, do not de sire to be limited or restricted to, as many modifications and changes in details and inst-rumentalities of application may be employed without departing from the spirit andv scope of my invention as defined in the claims.

In one arrangement shown, and referring particularly to Figs. 1 and 2, I employ a rail. which in this arrangement is other than a track rail, which I will call the safety control rail. This rail is sectional, that is, it is divided into short lengths, l 1", 1, etc, each section having". electrical connection with its adjacent sections through resistances 2, 2 2, etc. On each train there are two shoes, 3 andv 4.. bearing on the sectional rail 1, .1 one near the front end of the train, for example, 3, and: the other, for example l, near the rear end of the train. It is obvious where the system is employed with a single car, the two shoes 3 and a. would most effectively be at the front and rear ends of the car. Each of the shoes 8 and t is electrically connected to the power source. for example, the usual third. 'ail 5, through what I will term a meter 6,. which will be more fully hereinafter described. The electrical. current thus put lnto the sectional rail 1, at each point, would endeavor to pass along the sectional. rail in both directions, but as each section 1 1, 1, etc, of the rail 1 is connected to its adjoining sections through resistances 2, 2 2 etc, and as currents of equ il pressure are entering the sectional rail from each endof each train, the amount of current passing; through the meter 6 on any train can be measured by half the distance from the shoe 3 of that meter to the meter shoe ahead plus half the distance from the meter shoe 3 to the meter shoe in the rear.

' fore, any variation in thecurrent passing Ill) through the front meter would indicate only a variation in the distance of the train ahead. I have, therefore, devised a very simple and direct means whereby the distance, and the variance in the distance of the train ahead is measured in electrical energy on the train to be controlled, and I obtain this by using a common means for both the'preceding train and the following train so that the electrical effect as between the commonrmeans and the train to be controlled is governed by the distance of the train ahead, and without any mechanically operating mechanisms as essential parts thereof. It is manifest: that having obtained a variant in electrical energy on the controlled train that variesas the distance ahead of the preceding train, I can utilize this in many different ways to control the train movements. In one form the meter which will be hereinafter specifically described, is so constructed that whenever the passage of current theretlnrough is decreasing, the circuit is broken, which causes the power to be cut oif fronithe train controller and the brakes to be applied. hen, on the other hand, the meter current begins to increase and re-establish the circuit, it indicates'that the distance between the trains is increasing. I

In the arrangement described, I employ a continuous sectional rail, with resistances between the sections, and with other branch resistances from the sections to a common return conductor, which in this case is the ground. The electric current, therefore, is led from the source of power along the power or third rail, then through the rear of the preceding train and a portion thereof passes through the front of the following train into the sectional rail, then into a common return conductor, the ground, and the current passing through the front end of the following train varies with the distance between trains. Now it is manifest that my invention might be used. the other way around, that is, the circuit might lead from the source of power through a common insulated conductor, then through branch resistances to the sectional rail, then through the preceding and following trains, respectively. and then back by a common return, and there aresome marked advantages in this, as some decided economies can thereby of tl' etrains. each other, the lower the meter will register,

be effected. Under the former method four rails are necessary, two for traction or rightof-way, one for power, and one for the sectional rail, but under the latter method only two rails in all are necessary, with the addition of an insulated feed wire. Fig. 10 shows such an arrangement. It is to be understood that this method applies particularly to steam railroads where a power rail is not employed. A and B are the two rails on which the trains run. 13 is a continuous rail connected to the return of the source of power. A is a sectional rail, insulated from the ground or at least insulated suiticiently to prevent any material leakage of the low voltage current that would be used, andwith resistances between the sections, and with each section connected by branch resistances to a common feed wire C.

Now suppose D represents the rear wheels ot the preceding train, and E represents the front drawing wheels of the following train, and F represents the wheels of the pony truck of the engine of the following train. One of the wheels of F will be insulate-d from its axle, and so connected electrically to the other wheel of F, that current can only pass from one wheel of F to the other by passing through a meter on the engine.

New manifestly D and E each make a dead short circuit across from the sectional rail to the other rail B, and any current cmning from the feed wire C through the branch resistances between the trains would either find its way forward to D or backward to E and F. But inasmuch as F willbe continuously getting onto a section of rail, while E is On the-preceding section,the resistance between said sections will tend to force a part of said current to pass through F and so through the meter. The further part the trains, the greater the'number of branch resistances between the trains that will be bringing current into the sectional rail between the trains, and, therefore, the greater will he the current that is flowing forward and backward, and, therefore, the

greater will be the current passing through the meter, so that as before the meter position will correspond to the distance apart The nearer the trains are to and, therefore, an absence of power, or the breakage of a resistance will play tosafety by registerlng danger.

In Fig. 11 I show a still further modified arrangement wherein K is a continuous insulated cable extending along the right of way,

L a continuous insulated coil extending along the rightof way, A is the sectional track and B is the grounded track. In thr; arrangementthe effecton the meter -1S secured by induction from the coil L, thereby permltt'ing the use of alternating or oscilill) tin)

lailzing currents and avoiding the necessity of insulation as explained with reference to Fig. 10.

I will now describe the balance ot the equipment provided on the car which is diagra mmatically illustrated in Fig. 2. 8 desi gnatcs what- I will term, the brake and con trol solenoid. This solenoid is connected at one terminal tocontact 12 ot' the meter The other terminal is connected to a battery or other source of electrical energy 9, and the contact 12 is also connected to the battery through lamp 10. From the other side of the battery S) wire 11 leads to contact 13 of the meter (3,. and a branch wire leads through a push. button switch 14 to contact ot the meter. The solenoid 8 controls a contacting lever 15,. which when liberated operates to cut off the power and apply the brakes. Y

I will now describe the-meter 6. one form of which is illustrated in Figs. 3, l: and The meter is in the form; of a solenoid and comprises a. supporting member and base 17, carrying a frame, consisting? of studs 18 held by brackets 19' by being bolted thereto. A solenoid 2.0 is supported by the frame and is provided with a core 21, which is adapted to be drawn downwardly when the solenoid is energized. The solenoid core or plunger rod 21 has secured thereto an arm 22, through the ends of which pass the studs 18. coil spring 24 is mounted on each. of the studs 18, and extends to the-lower end thereof. and to the frame 23- of the solenoid 20. The upper parts of springs 24 support the arm 22 whereby, when the solenoid is energize-d, the arm 22 is drawn downwardly against the action of the springs 24 on studs 18.. It will be seen that when the solenoid is tie-energized; the plunger or core 21 is thrust upwardly. The core 21 has secured thereto a rod 25 of relatively smaller diameter, on which rod is loosely mounted a cup 26-, carrying conducting members 27 and 28 insulated from each other. The conducting ll'lGlDlJGIS 27 and 28 have flange portions 29 and 30, respectively, normally separated from each other, and aria-urged equidistantly from the rod. The rod 25 has secured thereto a bridging strip 31, to move coincidently therewitl'i. Thus, when the solenoid 20 is energized, the ln-idging strip 31 is drawn into contact with the flanges 29, 30, of the conducting strips 27, 28, to establish circuit connection therehetweeu. Contact lingers or springs 33,. bear at one end against conducting strips 27, 28, the other end being suitably secured to the base 17. The contact fingers 32, 33, exert a pressure on the cup so. the friction of which prevents the cup 26 from falling, due to gravity, and normally tends to hold the same yieldably in position relative to the rod 25. The cup 26 is provided with a collar 40, adaptedto nezmme form a bearingjfor the end of the core 21, to thereby move the cup upwardly when the solenoid 20 is tie-energized. Obviously, the bridging contact 31, hearing against the flanges 29, 30, of the cup moves the same downwardly when the magnet is energized, but with a certain drag due to the friction of the contact lingers 32', Rotative movement of the cup 26 is prevented due to th c nstruction,. best shown in Fig. 5, wherein the studs 18 pass therethrough.

it will. readily be seen from the foregoing that when the solenoid 20 is (lo-energized, the springs 2st on studs 18 force the arm 22, and consequently the core 21 upwardly. The end of the core 21 bears against. the collar of the cup 26. At the same time the rod 25, carrying the bridging contact 31 has been forced upwardly, breaking the connection. between the conducting strips 27, 28. Further upward movement of the plunger or core 21, caused by the action of the springs 24:, while maintaining the open position between the bridging strip 31 and conducting strips 27, 28, forces the cup 26 upwardlyto its limit of movement in an upward direction, i. e., the limit of expansion of the springs 24. Thereafter, it but little current is supplied the solenoid 20, the core will be drawn therein in proportion to the current supplied until the bridging member 31 establishes the circuit connection between the strips 27, 28, which is the position shown in the drawings. Further supply of current to the solenoid will merely tend. to cause the cup 26, to move downwardly with the rod 25. Contact finger 32 is supplied through wire 50 from a suitable source of current. Contact finger 33' is connected by wire 51 to the solenoid or other electrical device which controls the circuit of the power controller, brakes, &c. There are two ways by which current from a source or line' 5O may be supplied to wire 51. One is through the finger 32, strip 27, bridge 31, strip 28', to finger 33. Another way is through wire 52' through a push button switch 14.. There is a still further way which: is dependent upon the speed of travel of the train, which I will now describe. The frame 23 of the solenoid 20 isprovided with a lug 53, which forms a guide for the shaft 54, which is moved through the lug 53 by and in accordance with the speed of the train. Any suitable means may be employed for this purpose, for example, the means now generally employed in connection with train speedon'reters, or a speed governor directly applied to the rod 54. This rod carries secured thereto a conducting member 55. Interposed between the lug 50 and the contactor is a coil spring 56, normally tending to keep the contactor in an upward position. The contactor 55 is adapted to contact with a. conducting Ill! lit:

lit

also contact with the conducting strip mounted on rod 25, when the cup 26 is drawn downwardly by the $OlEI101tl QO a sufficient distance. The strip 57 isc'onnected by wire to the contact finger-'33, and hence by the wire 51 to the brake and con} trol solenoid. The operative parts 'of the meter thus far described in detail areshown in Fig. 2 diagrammatically where the finger 32 is represented by the terminal'13, finger 33, by the terminal 12, and the solenoid 20 by the meter 6. v

I will now describe the operation of the system, prefacing the same with the general statement that in accordance with my in-. vention 1 effect the automatic control, i. e.', the cutting off of the power and the application of the brakes, by means of opening a circuit; The particular device controlled by the opening of the circuit for accomplishing this shutting off of power and application of brakes, and in'fact for accomplishing any other desired operation, is well known in the art, and is extensively seed in it. Consequently, no specific means have been shown, it being apparent that an illustration of a circuit normally maintained closed under normal operating conditions, with means for opening that circuit to thereby release the action ofaspring, when the operating circuit is broken, is all that is necessary to those skilled in the art to enable a full application of the invention herein involved. Therefore, in connection with the meter construction shown and described with reference to Figs. 3, 1, and 5, it will be understood that it is to the solenoid 8 that the wire 51 leads, and that when the circuit through the wire 51 is broken, the auton'iatic safety devices are onerated. With the foregoing brief general explanation, the operation of the system thus far described is as follows;

Assume that the car is just starting in motion, traveling slowly, and the track ahead is clear. Under these conditions practically the full strength of current is passing through the solenoid 20. This means that the cup 26 has been drawn downwardly by the 'core 21 and bridging member 31' to its lower limit of movement, with the fingers 32, 33 hearing against the top of the conducting strips 27, 28, on the flanges 29 and 30. Circuit is thus established from the supply line 50, finger strip 27, bridge 31, strip 28, finger 33, wire 51, and in consequence the brakes are under the normal control of the motor-man, or other operator, as is likewise the power. This will permit the free normal operation of the car or train at any speed within the limit of the power of the car or train until the car or train approaches anupwardly,

be apparent that there other car or train on the same track ahead of it. Approaching another car in this manner W111, as is apparent, decrease the amount .of current that IS flowing through the solenoid 20, thereby diminishing the pull of the solenoid upon its core 21. This would cause the bridging member 31 to break the circuit between the flanges 29', 30 of the conducting strips 27 28, and in consequence would break the circuit to the wire 51, which, in the man-' ner hereinbefore' described would automatically cut off the power and apply the brakes,

until the car or train ahead had increased its separating distance sutiiciently to permit the current in the solenoid 20 to again draw the bridging member 31 into contact with the flanges 29, 30. It is apparent, however, that this decrease in distance might be effective to operatethe emergency control devices by breaking the circuit of the wire 51, when it is perfectly safe for the continued operation of'the car or train, as the distance might be decreasing and yet'be'well without the danger zone. Therefore, the speedon'ietercontrol 55, 56,57, etc, is ,sup-' plied. By means of this arrangement, when the fuil. current 1s flowing through the solenoid, as -a higher rate of speed is attained, the cup 26 in its downwardly drawn pos1- .tion establishes circuit connection between the line wire 50, finger 32, strip 57, con-' tactor 55, whiclndue to the speed attained, is in contactwiththe strip "57 and hence supplies current through wire 60 to wire 51. Therefore, it will be seen that even though the distance between trains is being reduced, and in consequence the circuit between strips 27, 28" is broken, if that distance is still far enough, so that the operation Oftllfi automatic safety device is not necessary, the normal control of the car is still maintained. If, however, the distance is further decreased without diminution of the speed, the continued decrease of; current in the, solenoid 20, allows the springs 24 to forcethe arm 22 forcing the cup 26 upwardly out of contact with the contactor55, and, therefore, the current to wire 51 will be broken; To putthe matter in a different way, it will are two circuits controlling the wire 51. One is controlled by the bridging member 31', and this is controlled entirely by the increasing or decreasing distance between the two trains. The other circuit is controlled by the strip 27 of cup 28, the contactor 55 and strip57, which in turn is controlled by the speed of the train conjointly with the distance between trains, and, therefore, if the distance is at any time diminishing between two trains, outside the V danger zone, one circuit is broken, but the other is not. When, however, within the danger zone, the distance between trains is diminishing, the circuit is tan'ce.

automatically broken, and, on the other hand, similarly, maximum speed is' allowed up to the limit of safety.

The foregoing system imposes a minimum restriction upon the carrying capacity of the road for the foregoing reasons. Further, it will be apparent that failure of any parts would automatically result in the application of the safety appliances, i. e., the breakof the circuit of wire 51. A failure of the front shoe to contact with the sectional rail would automatically break the circuit of wire 51. It is apparent that the current tl-i-rough the solenoid 20 would thus be shut off and cause both the brid e member 31 and the cup 26 to move upwardly. A failure of the rear shoe to contact with the sectional rail would increase the current passing through the front meter of that train, and through the front meter of the following train, but while these meters would thereupon be reading incorrectly in regard to the distance between the trains, they would still respond accurately to any variation of dis- In other words, due to the lag that exists between the bridging member 31 and the cup 26, by virtue of the frictional contacts 32, 33, irrespective of the amount of current that at any one time is passing through the solenoid 20, any decrease in that amount caused by the decrease of the distance separating trains would automatically break the circuit between the strips 27 and 28, and therewith of the wire 51. Therefore. any failure on one train will not cause a failure on any other train, and will at all times play to safety on its own train.

I will now describe the type of meter construction which I at present consider to be the preferred type, as is illustrated in Figs. 6 to 9, wherein various modifications in con struction are contemplated. In this arrangement, the solenoid 20 is located at the top of the supporting structure 17, with the plunger or core 21 depending therefrom. The plunger or core 21 is provided with an arm 22, normally pushed downwardly by the springs 24 on the frame studs 18, as hereinbefore described in connection with the structure of Figs. 3 to 5 inclusive. Secured to the end of the plunger 21 is a cup 26 hollow in shape, which carries the conducting strips 70, 71 and 72. Fingers 73, 74 and 75 bear against the respective conducting strips 70, 71 and 72. In this arrangement, as in that of Figs. 3 to 5, one of the fingers is connected :to the source of current supply, and each of the other fingers is connected to the control solenoid 8 as shown. Extending up through the center of the hollow cup 26 is the speed controlled rod 54, which rod is formed of varying diameters, each decreasing in size, 54, 54', 54 (see Fig. 12). On a portion of the rod 54 is loosely mounted a conducting bridging disk 80, the orifice therein through which 54 extends being of such size that the disk cannot move lower on the rod .54 than the next increasing diame ter thereof 54. The disk 80 is also of such diameter that when allowed to move downwardly relative to the cup 26 it will become seated between the conducting strips and 72. v A similar disk 81 of similar diamter for similarly bridging the circuit between conducting strips 70- and 71, is mounted on the portion 54 of rod 54, so that i't'will freely slide up and down thereon, but never passes over or surrounds the portion 54". The .p-or tion 54 of rod 54 is longer than the height of the strips 70 and 72. -t is understood that linger 73 corresponds to the finger 32 of the arrangement shown in Fig. 3, and similarly finger 75 corresponds to the finger shown in Fig. 3, current being at all times supplied to linger 7 The operation of the system thus far described will perhaps be better understood by reference to the diagrammatic illustration of Various positions of the cup'and bridging members 81 and set forth in Fig. 12.

Assume that the track ahead is clear, and

the train is stopped; with the train stopped, the speedometer rod 54 is at its lowest position relative to the solenoid 20, as shown in Fig. 12, where the base line illustrates the lowest limit of downward movement of the rod 54. Due to the fact that the track ahead is clear, solenoid 20 is receiving maximum current, with the result that the cup 26 and in consequence the strips 70, 71, 72, are drawn upwardly by the core of the sole noid to their upper limit of movement. Obviously the rod 54 being at its lowest limit of movement, permits the bridging members 81, 80, to establish a circuit connection from the contact 7 0 to the respective contacts 71 and The train is thereupon started, and the speed of the train is built up until the maximum speed is attained, but with the track, however, clear ahead, so that the maximum current is passing through the solenoid 20. This position is shown in the second diagram of Fig. 12. Here it will be seen the speedometer rod 54 has been projected upwardly to its maximum upward movement upon the train reaching its maximum speed, but due to the fact that the track is clear ahead, no alteration has occurred in the relative position of the conductors 70, 71, 72, and the bridging contacts 80 and 81. The train maintaining its max mum speed approaches a train immediately ahead, but the distance is still so great as to render maximum speed still safe. But, nevertheless, the fact that the danger area is being approached is called to the attention of the motorman. In the position shown in the third diagram of Fig. 12, it will be noted that the position of rod 54 has not changed, but the cup 26 and in consequence the strips 70, 72, have been lowered, due to thedecrease of current in the solenoid 20. Therefore, the bridging disk 81 has come to rest upon the end of the portion fil of the rod 54, and in consequence the continued downward movement of the strips 70, 71, 72, has lifted the bridging member 81 out of contact with the strips 2'0 and Ti.

which signal device is operative as long as currentis passing tl'ierethrough, but becomes inoperative when current ceases to pass therethrough in any suitable well known manner. Therefore, with the position thus attained by the respective cars, the signal becomes inoperative. In other words, the signal lamp going out is a signal of danger. If, in spite of the warning signal to the motorn'ian, the speed of the train is maintained, or the distance between the train-and the train ahead is further decreased so as to cause a further drop of the cup 26, the bridging strip 80 becomes seatedon the portion 54: of the speedometer rod 54, and due to the downward movement of the strips TO and 72, circuit connection is broken between the strips 70, 72, whereby the circuit of wire 51 is broken and the automatic devices operated. In other words, the current to the propelling motor of the caris broken, and the brakes are applied. This naturally causes the speed of the train to be reduced whereby the speedometer rod 54; is lowered. Vhenthe speed has been reduced to apoint where, relative to the distance separating the two trains, the border-line ofthe safety area exists, the bridging disk 80 is permitted to again establish circuit connection between the strips 70, 72, as shown in the next diagram of Fig. 12. The speed of the train is, however, Sutiiciently great in'connection with the separating distance of the trains so that the bridging disk 81 is still maintained out of contact with the strips 72 and 71, with the result that the signal is still extinguished, showing the motorman that he is still close to the danger zone, and should not attempt to increase the speed of his train or he will be in danger of having his power cut off and the brakes applied again, or, in other words, the emergency device operated. If the preceding train" is in motion, however, at a speed greater than the reduced speed of the train, so that the separating distance is increasii'ig, the cup' 26 is moved upwardly, due to the consequent increase of current passing through the solenoid 20, until the disk 21 again establishes circuit connection between the contacts 70, 71, and the signal indicates that the train is outside the danger zone. I 7

It may sometimes be desirable to permit, in the event of a block, the trains to approach each other without operating the safety devices, and it is i'orthis reason that Strip T1 is connected throughwire 101 to the signal device 102,

the push button switch '14, which is normally open, is provided. By closingtho switch 14 (see Fig. 3), it is possible tomaintain the circuit closed so that current is.

of either supplied to the wire 51 irrespective distance the speed of the train or of tne separating the two trains This nccessi-f tates, however, the motornian keeping his finger on the button, thereby ensuring his knowledge of the existence of danger, and

securing his utmost caution in the continued advance ofthe train. If at any time. while creeping up on a stalled train, his linger is removed from the. button, the automatic devices immediately operate to shut off his power and apply the brakes; In the event the block is lifted, and the preceding train proceeds in its travel, the train-control is again rendered operative, but the speed of the train is restricted to a speed equalto or or to a moving train; and all failures play tosafety. The relative distance at which the automatics would function can bevaried on grades by varying the size of the ground resistances at those places. i p

The speed of the'preceding train can be measured in the terms of the speed ofthe controlled train and of the increasing or .decreasing distance separating the trains. This makes it possible to combine the speed of the controlled train and the speedof the preceding train under the heading ofthe increase or decrease of the distance between trains.

It will be further seen that the power is cut off and the brakes applied in the event of either of the following happenings:

1. In the, event of any failure of any essential part.

2. Whenever the relative distance of the preceding train and the speed of the controlled train, and the decreasing separating distance, make it advisable.

Other things. being equal, the slower the speed of the controlled train, the nearer it can approach the train ahead before the automatics are operated. are liberated whenever the distance of the train ahead is increasing, or whenever the distance. when vcompared to the reduced speed of the controlled train, would make a nearer approach safe.- For example, in the The autoii'iatics speed ad distance used to illustrate, no particular attention has been given to select the correct distance-at which speeds would be a=llo able in practice. With that understanding, however, suppose train B going at 40 miles per hour is toliowing train A, going at 30 miles .per hour, with 2,000 feet separating distance. 'ilrain A con'nne-nces to slow up and stop at a station. By the time it has stopped, train 13 is only 1,000 feet behind. At this moment the automatics on train B are applied, and train B reduces its speed, sliding nearer to A as it does so. Let us suppose that the speed of train B is reduced to miles per hour when still 500 feet lironi the rear ot train A. If we assume this distance at this speed to be somewhat greater than a necessary minimum, then the auton'iat-ics would liberate, but they would go on again it train B ap proached too near to train A in proportion .to its speed.

Let us then suppose that when train B is 400 feet away, :and going 10 miles per hour, train A again starts. Just as soon as the speed of train A exceeds the speed of train B, so that the separating distance is increasing, the automatics on train 15 will be liberated by the completion ot the circuit of wire 51. Train B can then augment its speed almost .as fast as train A augment-s speed, and so long as the separating distance is not decreasing, train B is unattected, but :the instant train A starts to slow down, train B will. have its automaties set, unless the distance they are apart is n'mre than sutiicient to enable train B to stop at the speed at which it is operating.

If train A is :stopped at the bottom of a grade, and :train is coming towards A down the grade, then the eitl'ect on train Bs automatics would be the same as though train A were nearer to traiizi ll, but on a level track, than it actually is. In other words, other things being equal, the automatics on train B would set when a further distance in the rear when on a down grad, than they would when on a level grade, be.- cause of the varying values ot resistance employed on the sectional rail ground couneetions at the graded port-ion ot the track, as hereinabove described.

It will be seen that as the controlling meter on each train registers the variance in the separating distance, it will a'uton'iatically adjust itself to any temporary abnorn'ialities in the resistances, etc.

In the arran 'ement of Figs. (3 and 7, I show means which are simple, and which will permit the ready adjustn'ient ot the meter in accordance with the number of cars of the train. Obviously the cur-rent through sol-e- :noid on any train will vary in accordance both with the number of cars on the train and the distance ahead on. the preceding train. In order to enable the meter reading to correspond solely to the separating distance, I mount on a suitable bracket, 200, carried by the post 17, a graduated dial 201,, graduated in numbers of cars which constitute a train; the pointer 202 of the dial has secured thereto a cam handle 203, provided with a plurality of notches on the peripheral edge thereof. The studs it) have mounted thereon an arm 204:, and the arm is provided with a projection adapted to fit into the notch of the cam 203. Springs normally tending to maintain solenoid core 21 in the solenoid coil 20flare wound around the studs 18 between the two arms .22, 204:. It will, therefore, be apparent that by forcing downwardly the arm 204, and thereby increasing the tension of the springs 24- on studs 18, adj ustn'ient is secured proportional to the amount of current that would pass'through the solenoid, proportional to the number o t cars on the train, and by reason of the str.uc-' ture thus described, it is possible for the motorman to at the outset set his apparatus or pointer at the position where the proper amount ott tension is imparted to the springs 2A to completely compensate for current passing througl-i thesolenoid due to the number of cars of the train.

h lany modifications and changes in details will readily occur to those skilled in the art without departing from the spirit .and scope of my invention as defined in the claims, but having now set forth the objects and nature of my invention, and having shown a structure .en'ibodying the particulars thereof, what I claim as new and useiiu'l and of my own invention, and desire to secure by Letters Patent, is:

1. In a railway system, a plurality of trains, an unbroken electrical conductor, means for establishing an electrical circuit between each train and said conductor, an electrical device on each train included in said circuit, a safety circuit controlled by said device, and means for varying the curre-nt passing through said device by and in accordance with variation in the distance between the train on which said device is located and .the precedingtrain, the current passing through said device increasing with increase 0t distance between the trains, a signal, and means for operating said signal before said safety circuit is operated.

2. In a railway system, a plurality of trains, an unbroken electrical conductor, means tor establishing anelectrical circuit between each train and said conductor, an electrical device on each train included'in said circuit, a safety circuit controlled by controlled by'the speed of the train on whlch trical conductor, a train, a normally closed circuit for controlling safety devices on said train, and means operated by current in said conductorand controlled by the distance between said train and the preceding train,"

for opening said circuit when the train enters a danger zone, means adapted for vary ing the danger zone, a signal device, and means for operating said signal device prior to the opening of'said circuit.

4:. In a railway system, a common electrical conductor, a train, a normally closed circuit for controlling safety devices on said train, means operated by current in said conductor and controlled by the distance between said train and the preceding train for opening said circuit when the train enters a danger zone, said means, operated by current in said conductor, being also adapted for automatically closing said circuit when p the speed of said train is less than the speed of the preceding train,'a signal device and means for operating said signal device prior to the opening of said circuit.

5. In a railway system, a common electrical conductor, a train, a normally closed circuit for controlling safety devices on said train, and means operated by current in said conductor and controlled by the distance between said train and the preceding train, for opening said circuit when the train enters a danger zone, means adapted for varying the danger zone, a normally closed signal circuit, and means for opening said signal circuit prior to the opening of said safety circuit.

6. In a railway system, a commonv electrical conductor, a train, a normally closed circuit for controlling safety devices on said train, and means operated by current in said conductor and controlled by the distance between said train and the preceding train, for opening said circuit when the tram enters a danger zone, and means for automatically closing said circuit when the speed of said train is less than the speed of the preceding train, a normally closed signal circuit, and means for opening sa d slgnal circuit prior to the opening of sald safety circuit.

7. In a railway system, a common electrical conductor, a train, electrically operated safety devices 'on said train, a normally closed circuit for controllingsaid safety devices, means operated by current in said conductor and controlled by the distance between said train and the preoedingtrain foropening said circuit when the tram enters a danger zone, and means for mamta nmg taining said circuit open until the separating distance between said trains begins to increase, and means for intentionally mainsaid circuit closed temporarily irrespective of the distance between said trains.

8. In a railway system, a plurality of trains, safety devices carried thereby, a

means common to all trains for continuously controlling said safety devices, means for rendering said safety devicesvoper'ative on any train when said train enters a danger zone with reference to a preceding train,

means adapted for varying the danger zone, a signal device on each train, and means for operating said signal device before rendering said safety devices operative.

9. In a railroad system, a plurality oftrains, electrically controlled motive speed controlling means on each tram, a common means for continuously electrically afi'ecting the electrical control of said motlve speed controlling means on eachtrain and means carried on each train at each end for locally afiecting said common means tocontrol the next succeeding train, the current through said electrically controlled motive speed controlling means on said next succeeding train being proportional to one half the distance between the means on the forward end of said next succeeding train and the means on the rear of the train it is following plus one half the distance between the means on each end of said next succeeding train.

10. In a railway system, a plurality of trains, an unbroken electrical conductor, means for establishing an electrical circuit between'each train and said conductor, said means being mounted on each end of each train, an electrical device on each train in-' cluded in said circuit and means whereby the amount of current passing through said device on any train is indicative of the distance ahead of the preceding train, said unbroken electrical conductor and said means on each end of each train being so associated that the current through said electrical device is at all times proportional to one half the distance between the means on the rear ends of twoadjacent trains.

11. In a railway system, a plurality of trains, an unbroken electrical conductor, means'for establishing an electrical circuit between each train and said conductor comprising separate means on each end of each train, an electrical device on each train included in said circuit, means controlled by said device for controlling safety devices and means for varying the current passing through said device so that said current is continuously proportional to one half the distance between the means on the rear ends oftwo adjacent trains.

12. In a railway system, a plurality of trains, an unbroken electrical conductor,

means for establishing an electrical circuit between each train and said conductor, said means comprising a member on each end of each train, an electrical device on each train includedin said circuit, a safety circuit controlled by said device, means for varyingthe current passing through said device, the current variations being directly proportional to one half the distance between the members on the rear ends of two adjacent trains, means controlled by the speed of the train onwhich said device is located for also controlling said safety circuit, a signal and means for operating said signal before said safety circuit is operated.

'13. In a railway system, a plurality of trains, safety devices carried thereby, a means common to all trains for continuously controlling said safety devices, means for rendering said safety devices operative on any train when said train enters a danger zone with reference to a preceding train, electrical means on each train for controlling said safety devices, said electrical means being connected to said means common to all trains and arranged to he operatedliy a current proportional to onelialf the distance between two adjacent trains and means for adjust-ably setting said electrical means so the effect of thecurrent on said electrical means may lJQ-COIltlOllBCl to adapt the electrical'means for operation on trains of any length. i

In testimony whereof I have hereunto set my hand on this 20th day of March A. D. 1922.

HAROLD ROWNTBEE. 

